KR100848000B1 - Receiver for satellite broadcasting and receiving method - Google Patents

Abstract

A satellite broadcast receiving system and method are provided to allow a receiver to have a relatively low complexity compared with that of an existing receiver and exhibit fast adaptation in a fading environment. A correlation detecting unit(100) outputs a correlation between a reception signal transmitted from a transmission side and a PN(Pseudo Noise) code. A channel estimating unit(200) estimates channel characteristics from a correlation signal outputted from the correlation detecting unit and outputs the same. A combining unit(300) receives an output signal of the channel estimating unit and the reception signal, and combines them. A tap coefficient estimating unit(400) receives the output signal of the channel estimating unit and estimates a tap coefficient for channel compensation of the reception signal. A tap coefficient selecting unit(500) aligns tap coefficients received from the tap coefficient estimating unit in the order starting from a tap coefficient with the largest power, and selects tap coefficients corresponding to a designated multiple of the number of channel paths included in the output signal of the channel estimating unit in the order of power size. The combining unit selects one of the output signal of the tap coefficient selecting unit and the output signal of the channel estimating unit, combines the selected signal with the reception signal, and outputs the same.

Description

Satellite Broadcasting Receiving System and Receiving Method {Receiver for Satellite Broadcasting and Receiving Method}

1 is a configuration diagram of a satellite broadcast receiving system according to the present invention;

2 is a detailed configuration diagram of the correlation detector shown in FIG. 1;

3 is a detailed configuration diagram of a tap coefficient estimator shown in FIG. 1;

4 is a detailed configuration diagram of the tap coefficient selector shown in FIG. 1;

5 is a detailed configuration diagram of the coupling unit shown in FIG. 1;

6 is a graph for comparing the bit error rate according to the moving speed of the conventional satellite broadcasting receiver and the satellite broadcasting receiver according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: rake receiver 20: chip equalizer

100: correlation detector 200: channel estimator

300: coupling unit 400: tap coefficient estimation unit

500: tap coefficient selector 600: detector

101, 310, 410: delay 103, 320, 420: multiplier

105, 330, 430, 440: Adder 450: Tap coefficient update unit

The present invention relates to a communication system, and more particularly, to a satellite broadcasting receiving system and a receiving method capable of accurately recovering a received signal with a simple structure by applying a chip equalization technique in a receiving system based on a rake receiver.

Recently, as the user demand for high quality audio and video services increases, the commercialization of digital broadcasting services is expanding, and digital broadcasting can be classified into satellite broadcasting and terrestrial broadcasting.

For satellite digital broadcasting, the satellite base station receives broadcast data from each broadcasting station and transmits it to the satellite through an uplink transmission path of a designated band, and the satellite amplifies and frequency-converts the signal received from the satellite base station and transmits it toward the service area. do.

Accordingly, the receiver located in the satellite broadcast service area receives the broadcast signal from the satellite and reproduces the broadcast. And, in order to solve the problem that the signal is attenuated due to the shadowing or blocking due to buildings or shields, the broadcast signal is relayed using a gap filler.

In such a satellite broadcasting system, a transmission system transmits broadcast data using different orthogonal spreading codes in order to enable independent broadcasting for each broadcasting station and / or content, and in a receiving system, to distinguish different broadcast / content signals. Use Walsh code.

However, in the current satellite broadcasting reception system, the Walsh code orthogonality of the received signal is lost due to delay and frequency spread of the received signal in a multipath channel environment, and multi-channel interference may occur. In this case, the desired broadcast signal may not be correctly restored. There is a problem that can not be. This problem can be solved by reducing the interference signal, but in this case, the broadcast service channel is limited.

Therefore, a method for minimizing interference between received signals without restricting a broadcast channel has been studied, and one of the solutions is a method of introducing an equalizer to a reception system.

Equalization is a signal processing technique that compensates for distortion and interference on a channel such that a distorted signal transmitted from a transmitting end has a uniform amplitude and phase over the entire frequency band. A general equalizer has a fixed delay line with a tab attached thereto. The inter-signal interference is compensated for by adjusting the tap coefficient according to the delay characteristic of the input signal. The tap coefficient may be changed in accordance with the channel estimation information, and may be determined in accordance with noise signals, that is, delay signals distributed at delay positions around the main data signals. In other words, the tap coefficient is set to a value for removing the noise signal.

However, the equalizer currently used in the receiving system is complicated in configuration, takes a long time to acquire and update tap coefficients, and has a problem in that the performance of the receiving system cannot be guaranteed as the processing time is delayed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and provides a satellite broadcast receiving system capable of securing a larger number of broadcast channels in the same communication environment by introducing a chip equalization technique in a rake receiver-based receiving system. There is a problem.

Another technical problem of the present invention is to provide a satellite broadcast receiving system and method capable of quickly recovering a received signal at high speed by selecting a tap having excellent power according to a channel restoration result of a received signal and using the signal to restore the signal. There is a problem.

Another technical problem of the present invention is to simplify the configuration of a reception system for satellite broadcasting.

The satellite broadcast reception system according to an embodiment of the present invention for achieving the above-described technical problem is a satellite broadcast reception system consisting of a rake receiver and a chip equalizer, the rake receiver, the received signal and the PN code transmitted from the transmitting side; A correlation detector for outputting a correlation between the channel detector, a channel estimator for estimating channel characteristics from the correlation signal output from the correlation detector, and a combiner for receiving and combining the output signal and the received signal of the channel estimator; And a detector for restoring a broadcast signal from an output signal of the combiner, wherein the chip equalizer comprises: a tap coefficient estimator configured to receive an output signal of the channel estimator and estimate tap coefficients for channel compensation of the received signal; The tap coefficients received from the tap coefficient estimator are arranged in order of increasing power. A tap coefficient selector for selecting a tap coefficient corresponding to a specified multiple of the number of channel paths in order of power magnitude based on the number of channel paths included in an output signal of the channel estimator, and a bit error rate of a received signal. And a combiner configured to select one of an output signal of the tap coefficient selector and an output signal of the channel estimator and combine the selected signal with the received signal and output the combined signal.

In addition, the satellite broadcast reception method according to an embodiment of the present invention includes a first step of outputting a correlation between the received signal transmitted from the transmitting side and the PN code; A second step of estimating and outputting a channel characteristic from the correlation signal output in the first step; A third step of estimating a tap coefficient by receiving the channel estimated signal; And sort the estimated tap coefficients according to power magnitudes, and tap power corresponding to a specified multiple of the number of channel paths from the sorted tap coefficients based on the number of channel paths included in the channel estimated signal. A fourth step of selecting in order; A fifth step of selecting one of the channel estimated signal and the tap coefficient selected in the fourth step based on a bit error rate of a received signal; A sixth step of combining the signal selected in the fifth step with a received signal to output a combined signal; And a seventh step of recovering a broadcast signal from the combined signal.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a satellite broadcast receiving system according to the present invention.

As shown, the receiving system according to the present invention comprises a rake receiver 10 and a chip equalizer 20.

Here, the rake receiver 10 receives a signal r (i, n) transmitted from the transmitting side and outputs a correlation with the PN code from the correlation detector 100 and the correlation detector 100. The output signal and the received signal of the channel estimator 200 and the channel estimator 200 which receive the output correlation signal C_rx (i, n) and estimate channel characteristics through phase correction and channel delay detection. and a detector 300 for receiving r (i, n)) and outputting a combined signal, and a detector 600 for restoring the original broadcast signal using the output signal of the combiner 300.

In addition, the chip equalizer 20 receives the output signal of the channel estimator 200 and estimates the tap coefficient for channel compensation of the received signal. The tap coefficient estimator 400 and the channel estimator 200 output signals. And a tap coefficient selector 500 which receives the output signal of the tap coefficient estimator 400 and selects a tap coefficient of a specified level or more from the tap coefficients transmitted from the tap coefficient estimator 400 and provides the tap coefficient to the combiner 300. And a combiner 300 that receives the tap coefficient and the received signal r (i, n) output from the tap coefficient selector 500 and outputs a combined signal.

In the satellite broadcast receiving system of the present invention, the combiner 300 combines the received signal r (i, n) with the output signal of the channel estimator 200 or the output signal of the tap coefficient selector 500. Combine with To this end, if the bit error rate (BER) is greater than a preset reference error rate, for example, 1 * 10 ^-2 , based on the performance when the receiving system moves, the output signal of the tap coefficient selector 500 is used. Otherwise, by using the output signal of the channel estimator 200, it is possible to improve the performance of the receiving system and reduce complexity.

Meanwhile, in the satellite broadcasting reception system of the present invention, the tap coefficient estimator 400 delays the output signal of the channel estimator 200 for a predetermined time, multiplies the tap coefficients, adds all the multiplication results, and then The error value is calculated through comparison of and the tap coefficient is updated by applying an adaptive algorithm to the error value.

The updated tap coefficients are input to the tap coefficient selector 500, and the tap coefficient selector 500 sorts the tap coefficients according to the power levels, extracts a specified number of tap coefficients, and provides the tap coefficients to the combiner 300. .

As such, by selecting the tap coefficient with the large power level by the tap coefficient selector 500, the increase in power distribution can be reduced even when the number of taps is increased, and the amount of calculation can be minimized.

The configuration and operation of the reception system described above will be described in more detail with reference to FIGS. 2 to 5.

FIG. 2 is a detailed configuration diagram of the correlation detector shown in FIG. 1.

As shown in the drawing, the correlation detector 100 includes a first delay device comprising a plurality of delay elements (Tc) 101-1 to 101-n for delaying the received signal r (i, n) for a specified time. (101), each output of the first multiplier (103) and the first multiplier (103) consisting of multipliers (103-0 to 103-n) for multiplying the output signal of the first delay unit (101) and the PN code, respectively And a first adder 105 for summing the signals and outputting the correlation signal C_rx (i, n).

In this case, the correlation signal may be expressed as Equation 1 below.

[Equation 1]

Here, Rx (i, n) represents the received signal vector from the nth received signal of i-bit to the 2048th, and PN represents the 2048 PN code. The correlation signal is a complex signal and includes a real part and an imaginary part or a magnitude and a phase value and is input to the channel estimator 200.

The channel estimator 200 estimates channel information of the received signal by storing a correlation signal for a predetermined chip length. The channel information estimated by the channel estimator 200 is stored as a real part and an imaginary part or magnitude and phase information of each path, and is then input to the combiner 300.

On the other hand, the channel information estimated by the channel estimator 200 is also input to the tap coefficient estimator 400 and the tap coefficient selector 500. Same as

3 is a detailed block diagram of the tap coefficient estimator shown in FIG. 1.

The tap coefficient estimator 400 according to the present invention receives the output signal of the channel estimator 200 and delays the output signal of the second delayer 410 and the second delayer 410 and the tap coefficient for a predetermined time. The second multiplier 420 for multiplying, the second adder 430 for summing the output signals of the second multiplier 420, the second signal summing the output signal and the reference signal of the second adder 430 to output an error value And a tap coefficient updater 450 which updates the tap coefficients from the output signals of the third adder 440 and the third adder 440 and provides them to the second multiplier 420 and the tap coefficient selector 500.

In the tap coefficient estimator 400 illustrated in FIG. 3, the output signal of the second adder 430 becomes a 1-bit signal, and may be calculated by Equation 2 below.

[Equation 2]

는 i번째 생성된 비트 신호로 제 2 가산기(430)의 출력 신호가 된다.In Equation 2, g (i, n) means the n-th tap coefficient corresponding to the i-th sample position, Ch (i) represents the channel estimate of the i-th sample position,

Denotes the output signal of the second adder 430 as the i-th generated bit signal.

)는 오류값을 생성하기 위해 제 3 가산기(440)에서 기준신호(

)와 연산되며, 이 때 [수학식 3]을 이용할 수 있다.The output signal of the second adder 430 as described above

) Is a reference signal (3) in the third adder 440 to generate an error value.

) And [Equation 3] can be used.

[Equation 3]

The output signal of the third adder 440 is input to the tap coefficient updater 450. The tap coefficient updater 450 may update the tap coefficients by a recursive least square (RLS) algorithm or an adaptive algorithm similar thereto. In the case of using the RLS algorithm, Equations 4 to 5 below may be used. Through Equation 6, it is possible to update the tap coefficient.

[Equation 4]

[Equation 5]

[Equation 6]

Where k (i) is the gain vector of the i th sample, λ is the exponential weighting factor (value between 0 and 1), and P (i) is the inverse correlation matrix of the i th sample.

[Equation 5] is an equation for updating the tap coefficient by using the gain vector k (i) of the i th sample, and the tap coefficient is the tap coefficient of the previous sample, the error value of the current sample, and k (i). It is determined by the sum of the products.

Equation 6 is an equation for obtaining an inverse correlation matrix P (i), where H represents a Hermitian operation.

The tap coefficients g (i, n) updated in this way are input to the second multiplier 420, which are then used to update tap coefficients of a sample to be restored, and are input to the tap coefficient selector 450 to receive the received signal. Used to eliminate interference.

4 is a detailed configuration diagram of the tap coefficient selector shown in FIG. 1.

The tap coefficient selector 500 according to the present invention receives the updated tap coefficients from the tap coefficient estimator 400 and arranges the tap coefficients in the tab sorting module 510 and the tap sorting module 510. And a tap selection module 520 which extracts and outputs a specified number of taps from the coefficients (g '(i, n)).

More specifically, the tap sorting module 510 sorts the tap coefficients input from the tap coefficient estimating unit 400 in the order of the largest power, and the tap selecting module 520 designates the number according to the number of channel paths among the sorted taps. Extract tap coefficients and provide them to the coupling unit 300. Here, the number of tap coefficients to be extracted is preferably selected by N times the number of channel paths, and N can generally be set to three. In other words, tap coefficients equal to the number of channel paths * 3 are selected in order of increasing power.

When the tap coefficients are selected in this manner, power dissipation due to the increase in the number of taps is reduced, thereby improving bit error rate (BER) performance and reducing the amount of computation.

On the other hand, after the tap coefficient is selected by the tap coefficient selector 500, the combiner 300 selects any one of a signal received from the channel estimator 200 and a tap coefficient input from the tap coefficient selector 500. Combined with the received signal, this will be described with reference to FIG. 5.

5 is a detailed configuration diagram of the coupling unit shown in FIG. 1.

As shown in FIG. 5, the combiner 300 outputs a third delay unit 310 delaying the received signal for a predetermined time and outputs the output signal or tap of the channel estimator 200 according to the characteristics of the received signal. A switching unit 340 for selecting any one of the selection signals g '(i, n) extracted by the coefficient selecting unit 500, an output signal of the switching unit 340, and an output signal of the third retarder 310. And a fourth adder 330 that adds the output signals of the third multiplier 320 and the third multiplier 320 to the detection unit 600.

As described above, in the present invention, the switching unit 340 selects one of the output signal of the channel estimator 200 and the output signal of the tap coefficient selector 500 and combines the received signal to thereby convert the number of multipath channels. The performance of BER can be optimized by considering the moving speed of the receiver and receiver.

The first sample of the signal received from the transmitting side removes the interference from the received signal by using the output signal of the channel estimator 200 in the third multiplier 320, and from the subsequent samples, the channel estimator 200 according to the BER. After the interference is removed by the output signal or the tap coefficient selected by the tap coefficient selector 500, the detector 600 recovers the broadcast signal.

6 is a graph for comparing the bit error rate according to the moving speed of the conventional satellite broadcasting receiver and the satellite broadcasting receiver according to the present invention.

In FIG. 6, a, b, and c represent a bit error rate (BER) according to a moving speed of a receiver in a satellite broadcasting reception system using a rake receiver, and d, e, and f represent receivers in the satellite broadcasting receiving system according to the present invention. It represents the bit error rate (BER) according to the moving speed.

The parameters used in the computer simulation for FIG. 6 are channel # 0 (b, e), channel # 4 (c, f), channel # 19 (a, d), travel speed 10 km / h, 50 km / h, 100 km / h, 200km / h and fixed receive status. In addition, the initial value of the RLS parameter index weight factor for the tap coefficient update is set to 1.

As shown in the figure, in the case of a receiving system having only a conventional rake receiver (a, b, c), the performance change range according to the channel state or the mobile reception state is small, and the performance at the fixed reception is also affected by the interference according to the channel. It can be seen that there is deterioration.

On the other hand, in the case of the reception system according to the present invention (d, e, f) it can be seen that the interference by the channel is significantly removed. In addition, even when moving, performance cannot be guaranteed as in fixed reception, but it can be seen that the BER is improved compared to a reception system having only a conventional rake receiver.

In particular, BER of 1 * 10 ^- on the basis that the ^two, than this is not the case, to perform well, there is use of the extracted tap coefficient in the tap-coefficient selection unit proposed by the present invention, otherwise using the output signal estimation section channel Thus, the performance of the reception system can be further improved according to the characteristics of the reception signal.

As such, those skilled in the art will appreciate that the present invention can be implemented in other specific forms without changing the technical spirit or essential features thereof. Therefore, the above-described embodiments are to be understood as illustrative in all respects and not as restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

The satellite broadcasting reception system according to the present invention has excellent bit error rate performance and can secure a larger number of broadcast channels in the same communication environment. In addition, when the receiver moves, it has a lower complexity than the conventional receiver, and shows a fast adaptability in a fading environment.

Accordingly, since a large number of channels are secured at the transmitting end or a cell design has a wider service radius, and the receiver has a low complexity, power is advantageously secured, and thus a service for a longer time than the same power is available.

Claims (14)

A satellite broadcast receiving system comprising a rake receiver and a chip equalizer, The rake receiver includes a correlation detector for outputting a correlation between a received signal transmitted from a transmitter and a PN code, a channel estimator for estimating and outputting channel characteristics from the correlation signal output from the correlation detector; A combiner configured to receive and combine an output signal of the channel estimator and the received signal, and a detector configured to recover a broadcast signal from the output signal of the combiner; The chip equalizer may include a tap coefficient estimator configured to receive an output signal of the channel estimator and estimate a tap coefficient for channel compensation of the received signal, and a tap coefficient received from the tap coefficient estimator in order of increasing power. And a tap coefficient selector for selecting a tap coefficient corresponding to a specified multiple of the number of channel paths in order of power magnitude based on the number of channel paths included in the output signal of the channel estimator, and the bit error rate of the received signal. And a combiner configured to select one of an output signal of the tap coefficient selector and an output signal of the channel estimator, and combine and output the selected signal with the received signal. The method of claim 1, The tap coefficient estimator delays the output signal of the channel estimator for a predetermined time, multiplies the tap coefficient, adds a multiplication result, and then calculates an error value by comparing with a reference signal. The satellite broadcasting reception system, characterized in that for updating the tap coefficient. The method of claim 2, The tap coefficient estimator may include: a delayer configured to receive an output signal of the channel estimator and delay a predetermined time; A multiplier for multiplying the output signal of the delay and the tap coefficient; A first adder for summing output signals of the multiplier; A second adder for adding an output signal of the first adder and a reference signal to output an error value; And A tap coefficient updating unit for updating a tap coefficient from an output signal of the second adder and providing the tap coefficient to the multiplier and the tap coefficient selecting unit; Satellite broadcast reception system comprising a. The method of claim 3, wherein The tap coefficient updating unit updates the tap coefficients by a recursive least squares algorithm. delete delete delete The method of claim 1, The combiner may include: a delayer configured to delay and output a received signal for a preset time; A switching unit for selecting and outputting any one of an output signal of the channel estimator and an output signal of the tap coefficient selector based on a bit error rate of a received signal; A multiplier for multiplying an output signal of the switching unit and an output signal of the delay unit; And An adder for summing output signals of the multiplier and providing them to the detector; Satellite broadcast reception system comprising a. The method according to claim 1 or 8, And the combiner selects an output signal of the tap coefficient selector when the bit error rate of the received signal is greater than a preset reference error rate. A first step of outputting a correlation between a received signal transmitted from a transmitting side and a PN code; A second step of estimating and outputting a channel characteristic from the correlation signal output in the first step; A third step of estimating a tap coefficient by receiving the channel estimated signal; And sort the estimated tap coefficients according to power magnitudes, and tap power corresponding to a specified multiple of the number of channel paths from the sorted tap coefficients based on the number of channel paths included in the channel estimated signal. A fourth step of selecting in order; A fifth step of selecting one of the channel estimated signal and the tap coefficient selected in the fourth step based on a bit error rate of a received signal; A sixth step of combining the signal selected in the fifth step with a received signal to output a combined signal; And A seventh step of recovering a broadcast signal from the combined signal; Satellite broadcast receiving method comprising a. The method of claim 10, In the third step, the channel estimated signal is delayed for a predetermined time, multiplied by the tap coefficient, the multiplication result is added, an error value is calculated through comparison with a reference signal, and an adaptive algorithm is applied to the error value. And updating the tap coefficients. delete The method of claim 10, The sixth step may include a sixth-first step of delaying and outputting a received signal for a preset time; A 6-2 step of multiplying the signal selected in the fifth step with the signal delayed in the 6-1 step; And A 6-3 step of summing and outputting the multiplication result of the 6-6 step; Satellite broadcast receiving method comprising a. The method of claim 10, The fifth step selects the tap coefficient selected in the fourth step when the bit error rate of the received signal is greater than a preset reference error rate, and estimates the channel when the bit error rate of the received signal is equal to or less than the preset reference error rate. And a step of selecting a signal.

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